Figure 6

Titration of antibodies purified from enhancing and neutralising serum. IgG was purified by Protein G affinity chromatography from patient plasma taken on the same day as sera that enhanced and neutralised early patient virus, days 44 and 464 respectively. 10-fold serial dilutions of d44 and d464 IgG were tested against early autologous virus (MM24.26) and late autologous virus (MM24.464). The X-axes indicate IgG dilutions assayed relative to the IgG concentration in the original plasma source. Fold enhancement was calculated relative to infection in the presence of IgG purified from NHP. Identical assays performed with sera in the place of purified IgG are shown in the bottom panel for comparison. The horizontal dashed blue line indicates the cut-off point for positive C'-ADE. Error bars represent standard deviations from 3 experiments.